英文:
Golang - unable to parse JSON
问题
我开始学习GO，并遇到了这个问题。
我有以下代码：
package main
import (
"log"
"encoding/json"
)
func main(){
type Weather struct {
name string
cod float64
dt float64
id float64
}
var rawWeather = []byte(`{"name":"London","cod":200,"dt":1407100800,"id":2643743}`)
var w Weather
err := json.Unmarshal(rawWeather, &w)
if err != nil {
log.Fatalf("%s : 解析json时出错", err)
}
log.Printf("%+v\n",w)
}
当我运行它时，显示如下：
[nap@rhel projects]$ go run euler.go
{name: cod:0 dt:0 id:0}
所以，JSON没有解析到weather结构体中。
有任何想法，为什么会出现这种情况？
英文:
I've started learning GO, and i have encountered this issue.
I have this code
package main
import (
"log"
"encoding/json"
)
func main(){
type Weather struct {
name string
cod float64
dt float64
id float64
}
var rawWeather = []byte(`{"name":"London","cod":200,"dt":1407100800,"id":2643743}`)
var w Weather
err := json.Unmarshal(rawWeather, &w)
if err != nil {
log.Fatalf("%s : while parsing json", err)
}
log.Printf("%+v\n",w)
}
when i run it, it shows this
[nap@rhel projects]$ go run euler.go
{name: cod:0 dt:0 id:0}
So, the JSON is not parsed into the weather struct.
Any ideas, why do this happens like this?
答案1
得分: 7
你需要将结构字段的首字母大写。例如：
Name string
Cod float64
// 等等...
这是因为在尝试解组时，这些字段对于json包是不可见的。
Playground链接：http://play.golang.org/p/cOJD4itfIS
英文:
You need to capitalise your struct fields. E.g:
Name string
Cod float64
// etc..
This is because they are not visible to the json package when attempting to unmarshal.
Playground link: http://play.golang.org/p/cOJD4itfIS
答案2
得分: 1
这是因为Weather没有导出任何字段。这样修改：
type Weather struct {
Name string
Cod float64
Dt float64
Id float64
}
如果一个字段没有被导出，json包将无法访问它。你可以在这里找到更多信息：http://blog.golang.org/json-and-go，简而言之：
“json包只能访问结构体类型的导出字段（以大写字母开头的字段）。因此，只有结构体的导出字段会出现在JSON输出中。”
英文:
This is because Weather does not export any fields. This;
type Weather struct {
name string
cod float64
dt float64
id float64
}
Needs to be;
type Weather struct {
Name string
Cod float64
Dt float64
Id float64
}
If a field is not exported then the json package will not be able to access it. You can find more information about it here http://blog.golang.org/json-and-go but the short version is;
" The json package only accesses the exported fields of struct types (those that begin with an uppercase letter). Therefore only the the exported fields of a struct will be present in the JSON output."
答案3
得分: 0
通过猜测，我发现这段代码是有效的：
package main
import (
"fmt"
"encoding/json"
// "net/html"
)
func main(){
type Weather struct {
Name string
Cod float64
Dt float64
Id float64
}
var rawWeather = []byte(`[{"name":"London","cod":200,"dt":1407100800,"id":2643743}]`)
var w []Weather
err := json.Unmarshal(rawWeather, &w)
if err != nil {
fmt.Println("Some error", err)
}
fmt.Printf("%+v\n",w)
}
所以，结构体字段的名称必须大写才能正常工作！
英文:
By quessing, i found, that this code works:
package main
import (
"fmt"
"encoding/json"
// "net/html"
)
func main(){
type Weather struct {
Name string
Cod float64
Dt float64
Id float64
}
var rawWeather = []byte(`[{"name":"London","cod":200,"dt":1407100800,"id":2643743}]`)
var w []Weather
err := json.Unmarshal(rawWeather, &w)
if err != nil {
fmt.Println("Some error", err)
}
fmt.Printf("%+v\n",w)
}
So, the struct field names have to be Capitalized to work properly!
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论